When removing a disc from the spinal column, it is common practice for a surgeon to place a radiographically opaque needle into the exposed, potentially damaged disc and then view the needle via X-ray to ensure that the marked disc's location signifies that it is actually the damaged disc that is intended to be removed. Determining the location is often done by counting the vertebral bodies until the medical provider reaches the needled disc.
Unfortunately there are many problems associated with this practice. One such problem is that surgeons often puncture the wrong disc with the needle. This is understandably a common problem as the reason for using the needle is to verify whether the needled disc is in fact the damaged disc as opposed to a nearby healthy disc. Puncturing a healthy disc is undesirable in itself, but even more so when the needle pierces too far into the disc. While some have attempted to prevent over-piercing by using guards (See U.S. Pat. No. 5,195,526 to Michelson, hereinafter “Michelson I”, for example) the art does not appear to recognize that inserting marking devices into a healthy disc area is deleterious in itself, whether or not there is “over penetration.” Accordingly, there is a need to provide a system and method for radiographically determining the position of a damaged disc without potentially puncturing a healthy disc.
In addition to determining the position of an unhealthy disc, it is often also advantageous to use a marking system in order to determine the vertebral midline for proper graft, cage, and/or artificial disc implantation. Unfortunately, current systems and methods for determining the vertebral midline often involve piercing the disc space. See U.S. Pat. No. 6,224,607 to Michelson, hereinafter “Michelson II”, for example. This is disadvantageous for the same reasons as discussed above.
Marking systems used to determine the alignment of the vertebral midline or to ascertain whether a penetrated disc is damaged also overly rely on dyes for injecting into the disc space. The use of dye requires unnecessary steps in spinal marking that are more expensive, time consuming, requires a cannulated marker, and allows for more human error in the marking procedure.
A further disadvantage of current marking systems is that they are only used to mark the disc area, not to created additional, larger holes for other instruments used in spinal surgery.
Based on the above described problems, an objective of the teachings herein is to provide improved systems and methods for spinal marking that allow the operating surgeon to both identify the position of the damaged disc targeted for removal and to ascertain the position of the vertebral midline to allow for aligned implantation after removal of the damaged disc, or portions thereof. It is a further objective of the embodiments herein to provide a spinal marking system that does not rely on dyes or cannulated marking systems. Further objectives of the markers provided herein are to act as a designated point upon which a surgical instrument, such as a drill guide, can operably couple with to obtain proper alignment.